Vapor electric system



Oct. 14, 1941. J. H. cox ETAL 2,259,293

VAPOR ELECTRIC SYSTEM Filed Aug. 2, 1940 2 Sheets-Sheet l INVENTOE Jaseph Cox 0/70 Heal/317 M 69.

ATTORNEY WITNESSES:

Get. 14, 194 1. J. H. COX ETAL 2,259,293

- VAPOR ELECTRIC SYSTEM Filed Aug. 2, 1940 2 Sheets-Sheet 2 WITNESSES: INVENTORS I e ya/I.

v a. mm

. ATTORNEY Patented Oct. 14, 1941 UNITED STATES. PATENT OFFICE 2,259,293' 7 I VAPOR ELECTRIC SYSTEM Joseph H. Cox, Pittsburgh, and Henry C. Myers, Irwin, Pa., assignors to Westinghouse Electric 8; Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application August 2, 1940, Serial No. 349,656

3 Claims.

Our invention relates to a vapor-electric device, and particularly to a control system for a vapor-electric converter of the make-alive type.

In the operation of vapor-electric valves of the make-alive type, it has been found desirable to enclos the anode in asuitable anode shield in order to increase the stability andrating of the device. When using such anode shields, considerable difficulty has been encountered in reg-,

ularly establishing the main current-carrying are between the main anode and cathode. We have found that if suitable potential is applied to the anode shield, it serves as an exciting or ionizing device and greatly assists in the pick-up of the main arc in the device.

It is accordingly anobject of our invention to-v provide a control system for periodically applying control or exciting potentials to the anode shields of a make-alive type valve.

It is a further object of our invention to pro- In the illustrated embodiment of our inventionaccording to Figure 1, an altematlng-current circuit I is connected to a direct-current circuit 2 by means of a suitable connecting transformer 3. The secondary phase terminals of the connecting transformer 3 are connected to suitable electric valves 4 of the make-alive type for con-.

trolling the flow of current through the connecting transformer 3. Each of the make-alive type valves 4 comprises a suitable container 5, preferably of metal, which can be evacuated, a vaporizable reconstructing cathode of suitable. material, such as mercury, contained in the bottom of the container, 9. main anode] spaced from and insulated from the cathode B, an anode grid 8 preferably of conducting material, such as graphite, in closely spaced relation to the main former ill, the phase terminals ll of which are connected through suitable impedances l2 and' it to the make-alive electrode 9, and the fiow of current to the make-alive electrod js controlled by a suitable auxiliary rectifier or firing tube H, preferably of the grid controlled type. In order to conserve energy in the control transformer Ill,

suitable energy-storing devices, such as capacitors l5, are connected in parallelwith the phase windings [6 of the control transformer ill. The charging current of the capacitors I5 is controlled by suitable impedances [2, which may be either resistors or reactors, or a combinationof both. Also, the discharging current characteristic of the capacitors I5 is controlled by means of a suitable impedance l3, preferably of considerable less ohmic value than the impedance l2 between the phase terminal H and the capacitor II, so that the capacitor I5 is charged over a considerable interval of time, but the capacitor I8 is discharged in a much shorter interval of time to produce a peaked impulse for application to the make-alive electrode 9. Pr'ferably, the control transformer I0 is connecte in a phase relation advanced to the phase relation of the main transformer 3, so that the potential of the phase windings ill of the control transformer I0 is at its peak "value at the instant of starting the "cathode spoti'n, the make-alive typevalve l.

The. firing tubes are controlled by a suitable firing transformer 2ll the phase position of which may be controlled by any suitable means, such as the rotary phase shifter 2| interposed between the source of alternating-current 2 and the primary 22 of the firing transformer 20. Obviously,

by shifting the phase relation, the'firing instant can be changed at will with respect to the. phase position of the main transformer 3.

In order to insure pick-up of the main currentcarrying are after the establishment of the oath ode spot by the make-alive electrode 9, we have supplied an auxiliary source of excitation potential herein illustrated as an auxiliary transformer "25, although obviously any suitable source of anode 1, and a make-alive electrode 8 in permanent contact with the vaporizable cathode I. The make-alive electrode 9 is periodically supplied with energy to initiate a cathode spot for initiating a main current-carrying are between the anod 1 and the cathode 6.

' The current impulses. to the make-alive electrode 8 are supplied by a suitable control transpotential can be utilized. This auxiliary poten tial is connected to the anode shield 8 so that it forms an exciting, electrode adjacent to theanode I and brings the ionization into the vicinity of or in contact with the anode I, thus insuring ready pick-up of the main 'current-ca'rrying arc.

with or leading that or the main transformer 8, so that the exciting current to the shield 3 terminates with the termination of the current- Preferably, the phase relation of the. exciting transformer 25 is substantially in phase carrying are between the main anode? and cathode 6. V v

Inthe operation" of the converterv according to our invention, :potential isapplied to the control transformer ill and to the exciting'transformer 25 so that alternating current isapplied to the anode shields-8,' and the control transformer i0 charges the capacitors ii in readiness for initiat ing operation. The firing transformer 20 then releases the. firing ,tubes i4 so that the makealive valves 4 are successively periodically activated for the transfer of current between the;

alternating-current circuit I and the direct-current circuit 2 Obviously, the amount of current transferred can be controlled by the phase shifter 21 in series with the firing transformer 20.- The exciting transformer 25 supplies exciting current to the anode shields B which act as exciting electrodes, to ionize the arc space and insure ready pick-up of'the main current-carrying arc in the make-alive type valves 4.

The modification according to Fig. 2 is substan tially identical so far as the main current and igniting circuits are concerned, but the auxiliaryv transformer or exciting transformer 25 has been dispensed with, and arsuitable mid-tap 80 provided in each of the phase windings i6 inthe ,control transformer ill for supplying exciting current to the anode shields B which act as excit-' ing electrodes.

While for purposes of illustration I we have shown and described specific embodiments of our invention, it will be apparent that changes and,

, modifications can be made therein without cleparting from the true spirit of our inventionor the scope of the appended claims.

trol transformer for supplying control potential to the'make-alive electrode, means for periodically applying current impulses from said control transformer to said make-alive electrode for initiating a cathode spot in said make-alive valve,

'anauxiliary source of exciting potential independent of the load, 'and means for impressing the exciting of said auxiliary source on said anode shield.

2. An electric current conversion system comprising a plurality of make-alive type valves, each valve including an anode,a cathode, a make-alive electrode in contact with the cathode, and an anode shield about the anode, "a controlling transformer having a plurality of phase windings vconforming in number to the make-alive electrodes to be excited, at firing tube connected in series between each of said phaseowindings and said make-alive electrodes, means for determining the conductivity of said firing tubes, an in-' terinediate tap in each of said phase windings and connections for impressing the potential of 'said intermediate tap on said anode shield for ionizing the arc, space between the anode and cathode.

3. A control system for a vapor-electric valve i A of the make-alive type comprising a valve having a pair of cooperating main electrodes. aunakealive electrode in contact with one of said main. electrodes, a shield substantially enclosing the other main electrode, a control transformer, con-' nections for impressing the potential of said control transformer across the make alive electrode and the main eigctrodein contact therewith,

' intermediate tap on said shield.'

-means in said connections for controlling cur- ,rent flow to said make-alive electrode. an intermediate tap in said control transformer and circuit means for impressing the potential of said V 7 JOSEPH. H. cox. mare. MYER. s. i 

